During the coming year we intend to continue work on the following problems: 1. We shall attempt to determine the sequence and extent of changes in conductance which occur during slow synaptic signals in sympathetic neurons of the bullfrog. These slow synaptic potentials are initiated by the muscarinic action of ACh and also by the action of a new peptidergic transmitter which resembles luteinizing hormone releasing hormone (LHRH). 2. We shall explore further the ionic changes which generate the slow inhibitory synaptic potentials in C neurons of sympathetic ganglia.